John Baez's old web site has disappeared, presumably since he's no longer associated with the university whose server they were on. In particular his page on the relativistic rocket equations is gone, and that was a useful article for gathering all the equations together.

I was thinking of asking the question What are the equations describing the motion of a relativistic rocket? and posting a tidied up summary of the article as an answer. That way we have a copy in perpetuity (or until the SE goes bust :-).

But we aren't a blog and our mission isn't to save every physics blog that disappears, so I thought I'd check here before posting. If you want to check what I'm talking about a cached copy of the page is temporarily available here. I'd probably omit all the stuff about the fuel.

Opinions please - shall I go ahead?


Ah, it appears the article has not been deleted but has just been moved to this address. Thanks to John Duffield for pointing out its new location.

Panic over.

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    $\begingroup$ For when the cached copy evaporates: Wayback machine $\endgroup$ – Alfred Centauri Dec 2 '15 at 12:14
  • $\begingroup$ I think that if there is a good explanation for something that we might think will be a common question in the future, it would be good to document it here if there is no longer a link available. To me it seems like this type of question will almost inevitably come up again, and it would be good to be able to point people to it as a resource. $\endgroup$ – tmwilson26 Dec 2 '15 at 13:55
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    $\begingroup$ There are a few questions on the relativistic rocket (some answers as well, including some of yours). I wonder if it might be better to see if there is already an existing question and post a new answer to that, rather than writing from scratch. $\endgroup$ – Kyle Kanos Dec 2 '15 at 14:08
  • $\begingroup$ Good stuff John. Don't hesitate to get in touch with Don Koks the PhysicsFAQ editor about this sort of thing. Or indeed anything else. He's a good egg. And a "relativist" who knows his stuff. $\endgroup$ – John Duffield Dec 2 '15 at 19:51

It can't do any harm.

But I'm rather in the dark. I'm at work, I can't view the cached ratsauce page, it's classified as "personal sites". And I don't know what old web site you're referring to. There's this:


And this:


And then there's a relativistic rocket page which used to be this:


But now it's this:


Only that was written my Phil Gibbs and amended by Don Koks.


Sounds perfectly valid to me - of course, with the standard advice about making sure it is actually a question. I don't think this should be too hard in this case.

Incidentally, Baez's page wasn't a blog either. Not that that has much to do with anything.


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